JP2009231249A - Insulation sheet and laminated structural body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation sheet which has an excellent handlability and makes a curing material having excellent insulation breakdown property, thermal conductivity and heat resistance. <P>SOLUTION: The insulation sheet 3 is used for adhering a high temperature conductor 4 with a conductive layer 2 and contains polymer (A) having 30,000 or more of a weight average molecular weight, epoxy monomer (B1) and/or oxetane monomer (B2) having 600 or less of a weight average molecular weight with an aromatic frame, a curing agent (C) such as a phenol resin or the like, and a filler (D) with a high thermal conductivity. A bending elasticity modulus of the insulation sheet in a pre-curing status is 10-1,000 MPa at 25°C, a bending elasticity modulus of the curing material is 1,000-50,000 MPa at 25°C, and a tanδ of the insulation sheet in a pre-curing status measured by using a rotation type dynamic viscoelasticity measuring device is 0.1-1.0 at 25°C, and a maximum value of the tanδ of the insulation sheet when a temperature of the insulation sheet in the pre-curing status is raised from 25°C to 250°C is 1.0-5.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an insulating sheet used for bonding a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, and more specifically, has excellent handling properties in an uncured state, and The present invention relates to an insulating sheet that provides a cured product excellent in dielectric breakdown characteristics, thermal conductivity, heat resistance, and adhesiveness, and a laminated structure using the insulating sheet.

  In recent years, miniaturization and high performance of electric devices have been advanced. Along with this, the mounting density of electronic components is increasing, and the need to effectively dissipate heat generated from electronic components is increasing. As a method of dissipating heat, a method of adhering a high heat conductor such as aluminum having high heat dissipation and a thermal conductivity of 10 W / m · K or more to a heat source is widely adopted. . Further, an insulating adhesive material having an insulating property is used to bond the high thermal conductor to a heat source. This insulating adhesive material is strongly required to have a high thermal conductivity.

  As an example of the above insulating adhesive material, the following Patent Document 1 discloses an insulating material in which a glass cloth is impregnated with an adhesive composition containing an epoxy resin, an epoxy resin curing agent, a curing accelerator, an elastomer, and an inorganic filler. An adhesive sheet is disclosed.

On the other hand, insulating adhesive materials that do not use glass cloth are also known. For example, in the following Patent Document 2, an epoxy group-containing acrylic rubber having a weight average molecular weight of 100,000 or more, an epoxy resin, an epoxy resin curing agent, a curing accelerator, an epoxy resin and a weight are compatible. An insulating adhesive sheet containing a high molecular weight resin having an average molecular weight of 30,000 or more and an inorganic filler is disclosed. It is described that this insulating adhesive sheet has a minimum viscosity of 100 to 2000 Pa · s by a capillary rheometer method at a heating adhesion temperature.
JP 2006-342238 A Japanese Patent No. 3498537

  However, in the insulating adhesive sheet described in Patent Document 1, a glass cloth is used in order to improve handling properties. When glass cloth is used, it is difficult to make a thin film, and it is difficult to perform various processes such as laser processing and drilling. Furthermore, since the cured product of the insulating adhesive sheet containing glass cloth has a relatively low thermal conductivity, sufficient heat dissipation may not be obtained. Furthermore, special impregnation equipment had to be prepared in order to impregnate the glass cloth with the adhesive composition.

  On the other hand, since the insulating adhesive sheet described in Patent Document 2 does not use a glass cloth, the above-described various problems associated with the use of the glass cloth do not occur. However, this insulating adhesive sheet is required to have an adhesive function between a flexible wiring board and a semiconductor chip, and is required to exhibit stress relaxation as a low elastic modulus material. Therefore, this insulating adhesive sheet basically does not contain a filler, or even if it contains a filler, it contains only a small amount of about 33% by volume at maximum with respect to 100% by volume of the insulating sheet. For this reason, the insulating adhesive sheet described in Patent Document 2 has low thermal conductivity and insufficient heat dissipation.

  Here, in order to improve heat dissipation, when the highly heat-conductive filler is highly filled, the elastic modulus of the insulating adhesive sheet becomes too high to satisfy the parameters described in Patent Document 2. In addition, in order to enhance heat dissipation, when a high thermal conductivity filler is highly filled and an attempt is made to satisfy the parameters described in Patent Document 2, a large amount of a low molecular weight component is added to increase the viscosity. It needs to be adjusted. In this case, in an uncured state, tackiness becomes too high, and sufficient handling properties cannot be obtained.

  Moreover, the insulating adhesive sheet described in Patent Document 2 is added with acrylic rubber having a Tg of −10 ° C. or higher in order to develop stress relaxation properties in a cured state. However, when such a rubber component is added, there is a problem that the heat resistance of the cured product of the insulating adhesive sheet is lowered. Therefore, the insulating adhesive sheet described in Patent Document 2 is used for the purpose of heat dissipation of electronic components, particularly power of an electric vehicle or the like that generates a high amount of heat when a high voltage is applied or a large current flows. It was unsuitable for device use.

  The object of the present invention is used in order to adhere a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer in view of the above-described state of the prior art, and even if a glass cloth is not used, An object of the present invention is to provide an insulating sheet that provides a cured product having excellent handling properties in an uncured state and having excellent dielectric breakdown characteristics, thermal conductivity, heat resistance, and adhesiveness, and a laminated structure using the insulating sheet. .

  According to the present invention, there is provided an insulating sheet used for bonding a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer, the polymer (A) having a weight average molecular weight of 30,000 or more, and An epoxy monomer (B1) having an aromatic skeleton and a weight average molecular weight of 600 or less and / or an oxetane monomer (B2) having an aromatic skeleton and a weight average molecular weight of 600 or less, and a phenol resin Or an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a curing agent (C) that is a water additive thereof or a modified product thereof, and a filler (D) having a thermal conductivity of 30 W / m · K or more; In a total of 100% by weight of the resin component in the insulating sheet containing the polymer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), and the curing agent (C) The ratio of the polymer (A) is 20 to 60% by weight, the ratio of the epoxy monomer (B1) and / or the oxetane monomer (B2) is 10 to 60% by weight, and the polymer (A) and the epoxy monomer (B1) and / or the oxetane monomer (B2) is included in a ratio of less than 100% by weight, and the glass transition temperature of the uncured insulating sheet is 25 ° C. or less, and the uncured state The bending elastic modulus at 25 ° C. of the insulating sheet is in the range of 10 to 1000 MPa, and when the insulating sheet is cured, the bending elastic modulus at 25 ° C. of the cured product of the insulating sheet is in the range of 1000 to 50000 MPa. The tan δ of the uncured insulating sheet at 25 ° C. measured using a rotary dynamic viscoelasticity measuring device is in the range of 0.1 to 1.0, An insulating sheet having a maximum value of tan δ of 1.0 to 5.0 when an insulating sheet in an uncured state is heated from 25 ° C. to 250 ° C. is provided.

  In a specific aspect of the insulating sheet of the present invention, the polymer (A) has an aromatic skeleton. In this case, the heat resistance of the insulating sheet can be increased.

  In the present invention, various polymers can be used as the polymer (A), but a phenoxy resin is preferable, and thereby heat resistance can be further improved.

  In the present invention, various curing agents can be used as the curing agent (C), and the curing agent (C) is obtained by an addition reaction between an acid anhydride having a polyalicyclic skeleton or a terpene compound and maleic anhydride. An acid anhydride having an alicyclic skeleton, a water additive thereof, or a modified product thereof is also preferably used. Furthermore, an acid anhydride represented by any of the following formulas (1) to (3) is more preferably used as the curing agent (C). In these cases, the flexibility, moisture resistance and / or adhesion of the insulating sheet can be further enhanced.

  In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.

  In the present invention, various curing agents can be used as the curing agent (C), and a phenol resin having a melamine skeleton or a triazine skeleton or a phenol resin having an allyl group is preferable. In this case, the sheet flexibility and flame retardancy of the cured product of the insulating sheet are further enhanced.

  In the present invention, various fillers can be used as the filler (D), but at least one selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. Seeds are preferred, and spherical alumina and / or spherical aluminum nitride are more preferred. When these fillers (D) are used, the heat dissipation of the cured product of the insulating sheet can be further enhanced.

  In the laminated structure according to the present invention, a conductive layer is laminated on at least one surface of a high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer, and the insulating layer is configured according to the present invention. The insulating sheet thus formed is cured.

  In a specific aspect of the laminated structure according to the present invention, the high thermal conductor is a metal.

  In the insulating sheet according to the present invention, the components (A) to (D) are used in combination, and the uncured insulating sheet has a flexural modulus at 25 ° C. in the range of 10 to 1000 MPa, and is insulated. When the sheet is cured, the cured product of the insulating sheet has a flexural modulus at 25 ° C. in the range of 1000 to 50000 MPa, and is uncured at 25 ° C. measured using a rotary dynamic viscoelasticity measuring device. The maximum value of tan δ of the insulating sheet when the tan δ of the insulating sheet in the state is in the range of 0.1 to 1.0 and the insulating sheet in the uncured state is raised from 25 ° C. to 250 ° C. is 1. Since it is 0-5.0, the handleability in the uncured state of an insulating sheet can be improved, and also the hardened | cured material excellent in adhesiveness can be obtained by hardening an insulating sheet. Moreover, in the hardened | cured material obtained by hardening the insulating sheet which concerns on this invention, the outstanding dielectric breakdown characteristic, heat resistance, and heat conductivity can be acquired.

  In the laminated structure according to the present invention, a conductive layer is laminated on at least one surface of a high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer, and the insulating layer is configured according to the present invention. Since the formed insulating sheet is cured, heat from the conductive layer side is easily transferred to the high heat conductor through the insulating layer, and heat can be efficiently dissipated by the high heat conductor. Furthermore, in the laminated structure, it is possible to suppress the occurrence of dielectric breakdown or peeling at the adhesion interface.

  Details of the present invention will be described below.

  The insulating sheet according to the present invention includes a polymer (A) having a weight average molecular weight of 30,000 or more, an epoxy monomer (B1) having an aromatic skeleton and a weight average molecular weight of 600 or less, and / or an aromatic skeleton. And an oxetane monomer (B2) having a weight average molecular weight of 600 or less, a phenol resin, an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof, or a curing agent thereof (C) and a filler (D) having a thermal conductivity of 30 W / m · K or more.

  As a result of intensive studies to solve the above problems, the inventors of the present application have found that the polymer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), the curing agent (C), Adopting a composition in combination with the filler (D), and in this specific composition, the uncured insulating sheet has a flexural modulus at 25 ° C. in the range of 10 to 1000 MPa, and the insulating sheet is cured. The insulation modulus of the cured product of the insulating sheet at 25 ° C. is in the range of 1000 to 50000 MPa, and the insulation in the uncured state at 25 ° C. measured using a rotary dynamic viscoelasticity measuring device. The maximum value of tan δ of the insulating sheet when the tan δ of the sheet is in the range of 0.1 to 1.0 and the insulating sheet in the uncured state is raised from 25 ° C. to 250 ° C. is 1.0 to 5 It is found that by further providing a structure of 0.0, it is possible to obtain a cured product having not only excellent handling properties in an uncured state but also extremely excellent adhesion by curing the insulating sheet. The present invention has been achieved. Furthermore, it has also been found that a cured product obtained by curing the insulating sheet of the present invention can obtain excellent dielectric breakdown characteristics, heat resistance and thermal conductivity.

(Polymer (A))
The polymer (A) contained in the insulating sheet according to the present invention is not particularly limited as long as the weight average molecular weight is 30,000 or more. A polymer (A) may be used independently and 2 or more types may be used together.

  Since the polymer (A) can improve heat resistance, it preferably has an aromatic skeleton. The aromatic skeleton may be included in the entire polymer, may be included in the main chain skeleton, or may be included in the side chain. Since the heat resistance can be further improved, the polymer (A) preferably has an aromatic skeleton in the main chain skeleton.

  The aromatic skeleton is not particularly limited, and examples thereof include a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, and an adamantane skeleton. Especially, since heat resistance is further improved, a biphenyl skeleton or a fluorene skeleton is preferable.

  The polymer (A) is not particularly limited, and a thermoplastic resin or a thermosetting resin can be used.

  The thermoplastic resin and the thermosetting resin are not particularly limited. For example, thermoplastic resins such as polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetheretherketone, and polyetherketone, A heat-resistant resin group called super engineering plastics such as plastic polyimide, thermosetting polyimide, benzoxazine, and a reaction product of polybenzoxazole and benzoxazine can be used. These thermoplastic resins and thermosetting resins may be used alone or in combination of two or more. Moreover, a thermoplastic resin and a thermosetting resin may each be used independently, and both may be used together.

  Among the above polymers (A), oxidative degradation can be prevented and heat resistance can be further improved, so that a styrene polymer or a phenoxy resin is preferable, and among these, a phenoxy resin is more preferable.

  Specifically, the phenoxy resin is, for example, a resin obtained by reacting an epihalohydrin and a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound and a divalent phenol compound. is there.

  Examples of the phenoxy resin include bisphenol A skeleton, bisphenol F skeleton, bisphenol A / F mixed skeleton, naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton and dicyclopentadiene skeleton. Phenoxy resins having at least one skeleton selected from the group consisting of Among them, since the heat resistance can be further improved, at least one selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol A / F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, and a biphenyl skeleton. A phenoxy resin having a skeleton is more preferable, and a phenoxy resin having a fluorene skeleton and / or a biphenyl skeleton is still more preferable.

  The phenoxy resin preferably has a polycyclic aromatic skeleton in the main chain. The phenoxy resin more preferably has at least one skeleton among the skeletons represented by the following formulas (4) to (9) in the main chain.

In the above formula (4), R ₁ may be the same or different from each other and is a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen element, and X ₁ is a single bond or carbon. It is a group selected from a divalent hydrocarbon group of formulas 1 to 7, —O—, —S—, —SO ₂ —, or —CO—.

In the formula (5), R _1a may be the same as or different from each other, and is a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and R ₂ is a hydrogen atom, It is a group selected from a hydrocarbon group having 1 to 10 carbon atoms or a halogen element, R ₃ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and m is an integer of 0 to 5.

In the above formula (6), R _1b may be the same as or different from each other, and is a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and R ₄ is the same as each other. Or a group selected from a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, or a halogen element, and l is an integer of 0 to 4.

In the above formula (8), R ₅ and R ₆ are selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and a halogen atom, and X ₂ is —SO ₂ —, —CH ₂ —, —C ( CH ₃ ) ₂ — or —O—, and k is a value of 0 or 1.

  As said polymer (A), the phenoxy resin represented, for example by following formula (10) or following formula (11) can be used conveniently.

In the above formula (10), A ₁ has a structure represented by any of the above formulas (4) to (6), and the structure is 0 to 60 mol of the structure represented by the above formula (4). %, The structure represented by the above formula (5) is 5 to 95 mol%, and the structure represented by the above formula (6) is 5 to 95 mol%, and A ₂ is a hydrogen atom or the above formula (7 ), And n ₁ is an average value of 25 to 500.

In the above formula (11), A ₃ has a structure represented by the above formula (8) or the above formula (9), and n ₂ is a value of at least 21 or more.

  The glass transition temperature Tg of the polymer (A) is preferably in the range of 60 to 200 ° C, more preferably in the range of 90 to 180 ° C. If the Tg of the polymer (A) is too low, the resin may be thermally deteriorated. If the Tg is too high, the compatibility with other resins is deteriorated. As a result, the handling property of the insulating sheet and the cured product of the insulating sheet are deteriorated. Heat resistance may decrease.

  When the polymer (A) is a phenoxy resin, the glass transition temperature Tg is preferably 95 ° C or higher, more preferably 110 to 200 ° C, and still more preferably 110 to 180 ° C. If the Tg of the phenoxy resin is too low, the resin may be thermally deteriorated. If the Tg is too high, the compatibility with other resins deteriorates. As a result, the handling properties of the insulating sheet and the heat resistance of the cured product of the insulating sheet are reduced. May decrease.

  The polymer (A) has a weight average molecular weight of 30,000 or more. The weight average molecular weight of the polymer (A) is preferably in the range of 30,000 to 1,000,000, more preferably in the range of 40,000 to 250,000. If the weight average molecular weight is too small, thermal degradation may occur. If the weight average molecular weight is too large, compatibility with other resins is deteriorated. As a result, the handling property of the insulating sheet and the heat resistance of the cured product of the insulating sheet are lowered. Sometimes.

  In a total of 100% by weight of all resin components contained in the insulating sheet containing the polymer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), and the curing agent (C). The polymer (A) is 20 to 60% by weight, preferably 30 to 50% by weight, and the total of the polymer (A) and the epoxy monomer (B1) and / or oxetane monomer (B2) is 100. It is contained in a proportion of less than% by weight. When there are too few polymers (A), the handleability of an insulating sheet may fall, and when there are too many, dispersion | distribution of a filler (D) may become difficult. The total resin component means the sum of the polymer (A), the epoxy monomer (B1), the oxetane monomer (B2), the curing agent (C), and other resin components added as necessary. .

(Epoxy monomer (B1) and oxetane monomer (B2))
The insulating sheet according to the present invention has an aromatic skeleton and an epoxy monomer (B1) having a weight average molecular weight of 600 or less, and / or an oxetane monomer having an aromatic skeleton and a weight average molecular weight of 600 or less ( B2). The insulating sheet may contain only one of the epoxy monomer (B1) and the oxetane monomer (B2), or may contain both.

  The epoxy monomer (B1) is not particularly limited. For example, an epoxy monomer having a bisphenol skeleton of bisphenol A type, bisphenol F type or bisphenol S type; a phenol novolak having a dicyclopentadiene dioxide or dicyclopentadiene skeleton. Epoxy monomers having a dicyclopentadiene skeleton such as epoxy monomers; 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7 Epoxy monomers having a naphthalene skeleton such as diglycidylnaphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene; 1,3-bis ( -Epoxy monomer having an adamantene skeleton such as glycidyloxyphenyl) adamantene and 2,2-bis (4-glycidyloxyphenyl) adamantene; 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4 -Glycidyloxy-3-methylphenyl) fluorene, 9,9-bis (4-glycidyloxy-3-chlorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-bromophenyl) fluorene, 9,9- Bis (4-glycidyloxy-3-fluorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-methoxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dimethylphenyl) Fluorene, 9,9-bis (4-glycidyloxy-3,5-di (Lolophenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) fluorene and other epoxy monomers having a fluorene skeleton, 4,4′-diglycidylbiphenyl, 4,4′-diglycidyl-3, Epoxy resins having a biphenyl skeleton such as 3 ′, 5,5′-tetramethylbiphenyl; 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxy) Naphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyl) Oxynaphthyl) methane, 1,8′-bi (3,5-glycidyloxynaphthyl) methane, 1,2′-bi (2,7-glycidylo) Epoxy having a bi (glycidyloxyphenyl) methane skeleton such as xylnaphthyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,5-glycidyloxynaphthyl) methane Monomer; Epoxy monomer having xanthene skeleton such as 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene; having anthracene skeleton or pyrene skeleton An epoxy monomer etc. are mentioned. As for these epoxy monomers (B1), only 1 type may be used and 2 or more types may be used together.

  The oxetane monomer (B2) is not particularly limited. For example, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, bis-1,4-benzenedicarboxylate [(3- Ethyl-3-oxetanyl) methyl] ester, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, oxetated phenol novolac and the like. As for these oxetane monomers (B2), only 1 type may be used and 2 or more types may be used together.

  The epoxy monomer (B1) and / or oxetane monomer (B2) has a weight average molecular weight of 600 or less. The preferable lower limit of the weight average molecular weight of the epoxy monomer (B1) and / or the oxetane monomer (B2) is 200, and the preferable upper limit is 550. If the weight average molecular weight is too small, the volatility is too high and the handleability of the insulating sheet may be lowered. If it is too large, the sheet may be hard and brittle, or the adhesive force may be lowered.

  When the epoxy monomer (B1) and the oxetane monomer (B2) are used in combination or when any one of them is used, the polymer (A), the epoxy monomer (B1) and / or the oxetane monomer ( In total 100% by weight of all resin components contained in the insulating sheet containing B2) and the curing agent (C), the epoxy monomer (B1) and / or oxetane monomer (B2) is 10 to 60% by weight. , Preferably 10 to 40% by weight, and the total of polymer (A) and epoxy monomer (B1) and / or oxetane monomer (B2) is less than 100% by weight.

  When there are too few epoxy monomers (B1) and / or oxetane monomers (B2), adhesiveness and heat resistance may fall, and when too much, the softness | flexibility of an insulating sheet may fall.

(Curing agent (C))
The curing agent (C) contained in the insulating sheet according to the present invention is a phenol resin, an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof, or a modified product thereof. By using this hardening | curing agent (C), the hardened | cured material of the insulating sheet excellent in heat resistance, moisture resistance, and the balance of an electrical property can be obtained. A hardening | curing agent (C) may be used independently and 2 or more types may be used together.

  The phenol resin is not particularly limited, but phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene modified novolak, decalin modified Examples include novolak, poly (di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, poly (di-p-hydroxyphenyl) methane, and the like. Especially, since a sheet | seat softness | flexibility and a flame retardance are improved further, the phenol resin which has a melamine skeleton, the phenol resin which has a triazine skeleton, or the phenol resin which has an allyl group is preferable.

  Examples of commercially available phenol resins include MEH-8005, MEH-8010, NEH-8015 manufactured by Meiwa Kasei Co., Ltd .; YLH903 manufactured by Japan Epoxy Resin; LA-7052, LA-7054, LA- 7751, LA-1356, LA-3018-50P; PS6313 and PS6492 manufactured by Gunei Chemical Co., Ltd.

  An acid anhydride having an aromatic skeleton, a water additive thereof, or a modified product thereof is not particularly limited. For example, styrene / maleic anhydride copolymer, benzophenone tetracarboxylic acid anhydride, pyromellitic acid anhydride, trimellitic acid Anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydrophthalic anhydride, methyl Examples include hexahydrophthalic anhydride and trialkyltetrahydrophthalic anhydride. Of these, methylnadic acid anhydride and trialkyltetrahydrophthalic anhydride are preferable because water resistance is improved.

  Examples of commercially available acid anhydrides having an aromatic skeleton, water additives thereof, and modified products thereof include SMA Resin EF30, SMA Resin EF40, SMA Resin EF60, and SMA Resin EF80 manufactured by Sartomer Japan; manufactured by Manac ODPA-M, PEPA; Rikagit MTA-10, Rikagit MTA-15, Rikagit TMTA, Rikagit TMEG-100, Rikagit TMEG-200, Rikagit TMEG-300, Rikagit TMEG-500, Rikagit TMEG-S, manufactured by Shin Nippon Chemical Co., Ltd. Rikagit TH, Rikagit HT-1A, Rikagit HH, Rikagit MH-700, Rikagit MT-500, Rikagit DSDA, Rikagit TDA-100; EPICLON B4400, EPICLON B65 manufactured by Dainippon Ink & Chemicals, Inc. 0, EPICLON B570 and the like.

  Moreover, as an acid anhydride having an alicyclic skeleton, a water additive thereof, or a modified product thereof, an acid anhydride having a polyalicyclic skeleton, an alicyclic ring obtained by an addition reaction of a terpene compound and maleic anhydride An acid anhydride having a formula skeleton, a water additive thereof or a modified product thereof is preferred. In this case, the flexibility, moisture resistance, and / or adhesiveness of the insulating sheet can be further enhanced. Examples of the acid anhydride having an alicyclic skeleton, a water additive thereof, or a modified product thereof include methyl nadic acid anhydride, an acid anhydride having a dicyclopentadiene skeleton, or a modified product thereof.

  Examples of commercially available acid anhydrides having the alicyclic skeleton, water additives thereof, or modified products thereof include Rikajito HNA and Rikajito HNA-100 manufactured by Shin Nippon Rika Co., Ltd .; EpiCure YH306 and EpiCure YH307 manufactured by Japan Epoxy Resin Co., Ltd. Epicure YH308H, Epicure YH309, and the like.

  Moreover, since the softness | flexibility of a sheet | seat, moisture resistance, and / or adhesiveness can be improved further as said hardening | curing agent (C), the acid anhydride represented by either of following formula (1)-(3). More preferred.

  In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.

  In order to adjust the curing speed and the physical properties of the cured product, a curing accelerator may be used in combination with the curing agent.

  The curing accelerator is not particularly limited. For example, diazabicycloalkenes such as tertiary amines, imidazoles, imidazolines, triazines, organic phosphorus compounds, quaternary phosphonium salts, and organic acid salts; octylic acid Organometallic compounds such as zinc, tin octylate and aluminum acetylacetone complex; quaternary ammonium salts; metal halides.

  Examples of the curing accelerator include high melting point imidazole compounds, dicyandiamide, or high melting point dispersion type latent accelerators such as amine addition type accelerators in which an amine is added to an epoxy monomer, imidazole-based, phosphorus-based or phosphine-based accelerators. Microcapsule-type latent accelerators coated with polymer, amine salt-type latent curing accelerators, high-temperature dissociation type thermal cationic polymerization type latent curing accelerators such as Lewis acid salts and Bronsted acid salts Representative latent curing accelerators can also be used. Especially, since it is easy to control the reaction system for adjusting a cure rate, the physical property of hardened | cured material, etc., a high melting point imidazole type hardening accelerator is used suitably. These hardening accelerators may be used independently and 2 or more types may be used together. Since the handleability is excellent, the curing accelerator preferably has a melting point of 100 ° C. or higher.

(Filler (D))
The filler (D) contained in the insulating sheet according to the present invention is not particularly limited as long as the thermal conductivity is 30 W / m · K or more. A filler (D) may be used independently and 2 or more types may be used together.

  The filler (D) having a thermal conductivity of 30 W / m · K or more is preferably at least one selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide and magnesium oxide. . Especially, since heat dissipation can be improved further, spherical alumina and / or spherical aluminum nitride are more preferable.

  The average particle size of the filler (D) is preferably in the range of 0.1 to 40 μm. When the average particle size is less than 0.1 μm, high filling may be difficult, and when it exceeds 40 μm, the dielectric breakdown characteristics may be deteriorated.

  As a compounding quantity of the said filler (D), the range of 50-90 volume% is preferable in 100 volume% of insulating sheets. If the filler (D) is less than 50% by volume, the heat dissipation may not be sufficiently improved, and if it exceeds 90% by volume, the flexibility and adhesiveness of the insulating sheet may be significantly reduced.

(Other ingredients)
The insulating sheet according to the present invention may contain a base material such as glass cloth, glass nonwoven fabric, and aramid nonwoven fabric in order to further improve handling properties. However, even if these base materials are not included, the insulating sheet of the present invention is self-supporting even in an uncured state at room temperature (23 ° C.) and has excellent handling properties. Therefore, the insulating sheet preferably does not contain a base material, and particularly preferably does not contain glass cloth. When the base material is not included, the insulating sheet can be made thin, and the thermal conductivity of the insulating sheet can be further increased. Further, if necessary, the insulating sheet is laser processed, drilled, etc. These various processes can be easily performed. In addition, self-supporting means that the shape of the sheet can be maintained and handled as a sheet even in the absence of a support such as a PET film or copper foil, even in an uncured state. And

  Moreover, the insulating sheet of the present invention may contain a thixotropic agent, a dispersant, a flame retardant, a colorant, and the like as necessary.

(Insulating sheet)
The insulating sheet according to the present invention is not particularly limited, but can be obtained, for example, by molding a mixture of the above-described materials into a sheet shape by a method such as a solvent casting method or an extrusion film forming method. Defoaming is preferred when forming into a sheet.

  The glass transition temperature (Tg) in the uncured state of the insulating sheet according to the present invention is 25 ° C. or lower. When the glass transition temperature exceeds 25 ° C., the glass transition temperature may be hard and brittle at room temperature, which causes a decrease in handling properties of the insulating sheet.

  The bending elastic modulus in 25 degreeC in the uncured state of the insulating sheet of this invention exists in the range of 10-1000 MPa. More preferably, it is the range of 20-500 MPa. If the bending elastic modulus at 25 ° C. in the uncured state of the insulating sheet is less than 10 MPa, the self-supporting property of the insulating sheet in the uncured state at room temperature may be significantly reduced and the handling property may be inferior, and 1000 MPa If it exceeds, the elastic modulus will not be sufficiently lowered even during heat bonding, so that the adhesion of the cured product of the insulating sheet to the bonding target may occur, or the adhesive strength between the insulating sheet and the bonding target may be inferior. .

  The bending elastic modulus at 25 ° C. of the cured product of the insulating sheet when the insulating sheet of the present invention is cured is in the range of 1000 to 50000 MPa. More preferably, it is the range of 5000-30000 MPa. When the bending elastic modulus at 25 ° C. of the cured product of the insulating sheet is less than 1000 MPa, for example, when the insulating sheet of the present invention is used to produce a laminated body such as a thin laminated board or a double-sided copper foil laminated board. The obtained laminate is easy to bend and may cause breakage or breakage due to bending. If it exceeds 50000 MPa, the cured product becomes too hard and brittle, and cracks and the like may easily occur.

  The bending elastic modulus is, for example, a universal tester RTC-1310A (manufactured by Orientec Co., Ltd.) based on JIS K 7111. It can be measured under the condition of 1.5 mm / min. Moreover, when measuring the bending elastic modulus of hardened | cured material, the hardened | cured material of an insulating sheet can be obtained by making it harden | cure by the temperature of two steps of 120 degreeC for 1 hour and then 200 degreeC for 1 hour.

  In the insulating sheet according to the present invention, the tan δ of the uncured insulating sheet at 25 ° C. measured using a rotary dynamic viscoelasticity measuring device is in the range of 0.1 to 1.0, preferably 0. A range of 1.0 to 5.0, and the maximum value of tan δ of the insulating sheet when the temperature of the uncured insulating sheet is raised from 25 ° C. to 250 ° C. Preferably it is the range of 1.5-4.0.

  When the tan δ of the uncured insulating sheet at 25 ° C. is less than 0.1, the flexibility of the uncured insulating sheet is insufficient and the uncured insulating sheet may be easily damaged. If it is 1.0 or more, the uncured insulating sheet is too soft, and the sheet handling property of the uncured insulating sheet may be inferior. Further, when the maximum value of tan δ of the insulating sheet when the insulating sheet in the uncured state is raised from 25 ° C. to 250 ° C. is less than 1.0, the insulating sheet for the object to be bonded at the time of heat bonding Adhesiveness may be insufficient. If it exceeds 5.0, the fluidity of the insulating sheet is too high, and the insulating sheet becomes thinner than the desired film thickness at the time of heat bonding, and the desired dielectric breakdown characteristics may not be obtained.

  The tan δ of the uncured insulating sheet at 25 ° C. is a disk-shaped uncured insulating sheet having a diameter of 2 cm, using a rotary dynamic viscoelasticity measuring device VAR-100 (manufactured by Rheologicala Instruments). Using a sample, a parallel type plate having a diameter of 2 cm can be measured at 25 ° C. under the conditions of an oscillation strain control mode, a starting stress of 10 Pa, a frequency of 1 Hz, and a strain of 1%. In addition, the maximum value of tan δ of the insulating sheet when the insulating sheet in the uncured state is heated from 25 ° C. to 250 ° C. is obtained by adding the uncured insulating sheet sample to the measurement conditions and increasing the rate of temperature increase. It can be measured by raising the temperature from 25 ° C. to 250 ° C. at 30 ° C./min.

  The characteristics of the present invention were measured using a bending elastic modulus at 25 ° C. of an uncured insulating sheet, a bending elastic modulus at 25 ° C. of a cured product of the insulating sheet, and a rotary dynamic viscoelasticity measuring device. The maximum value of the tan δ at 25 ° C. of the uncured insulating sheet and the tan δ of the insulating sheet when the insulating sheet in the uncured state is heated from 25 ° C. to 250 ° C. is in the specific range. is there. When the bending elastic modulus and tan δ are within the specific range, the obtained insulating sheet has extremely high handling properties at the time of manufacture and use, and using this insulating sheet, copper foil or aluminum When a high thermal conductor such as a plate is bonded to the conductive layer, extremely high adhesive strength can be obtained. Moreover, when the bonding surface of the high thermal conductor has irregularities, the followability of the insulating sheet to the irregularities can be improved. Furthermore, since the followability with respect to the unevenness of the insulating sheet is improved, it is difficult for voids to be formed at the adhesive interface, and thus the thermal conductivity can be increased.

  Although it does not specifically limit as a film thickness of an insulating sheet, The range of 10-300 micrometers is preferable. More preferably, it is the range of 30-200 micrometers, Most preferably, it is 40-100 micrometers. If the film thickness is too thin, the insulating property may be lowered, and if it is too thick, the heat dissipation may be lowered when the metal body is bonded to the conductive layer.

  The thermal conductivity after curing of the insulating sheet is preferably 2.0 W / m · K or more. More preferably, it is 3.0 W / m * K or more, More preferably, it is 5.0 W / m * K or more. If the thermal conductivity is too low, sufficient heat dissipation may not be obtained.

  The dielectric breakdown voltage after curing of the insulating sheet is preferably 30 kV / mm or more. More preferably, it is 40 kV / mm or more, More preferably, it is 50 kV / mm or more. If the dielectric breakdown voltage is too low, sufficient insulation may not be obtained when used for high current applications such as for power devices.

The volume resistivity after curing of the insulating sheet is preferably 10 ¹⁴ Ω · cm or more. More preferably, it is 10 ¹⁶ Ω · cm or more. If the volume resistivity is too low, insulation between the conductor layer and the high thermal conductor may not be maintained.

  The coefficient of thermal expansion after curing of the insulating sheet is preferably 30 ppm / ° C. or less. More preferably, it is 20 ppm / ° C. or less. If the coefficient of thermal expansion is too high, the thermal cycle resistance may be inferior.

(Laminated structure)
The insulating sheet according to the present invention is used to bond a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer. The insulating sheet according to the present invention constitutes an insulating layer of a laminated structure in which a conductive layer is laminated on at least one surface of a high thermal conductor having a thermal conductivity of 10 W / m · K or more via an insulating layer. It is used suitably for. For example, by bonding a metal body via an insulating sheet to each conductive layer such as a laminated board with a double-sided copper circuit or a multilayer wiring board, copper foil, copper plate, semiconductor element, semiconductor package, etc., by curing the insulating sheet, The laminated structure can be obtained.

  In FIG. 1, the laminated structure which concerns on one Embodiment of this invention is typically shown with a partial notch front sectional drawing.

  In the laminated structure 1 shown in FIG. 1, a high thermal conductor 4 is laminated on a surface 2 a of a conductive layer 2 as a heat source via an insulating layer 3. The insulating layer 3 is formed by curing the insulating sheet of the present invention. As the high thermal conductor 4, a high thermal conductor having a thermal conductivity of 10 W / m · K or more is used.

  In the laminated structure 1, since the insulating layer 3 has a high thermal conductivity, heat from the conductive layer 2 side is easily transferred to the high thermal conductor 4 through the insulating layer 3. And heat can be efficiently dissipated by the high thermal conductor 4.

  The high thermal conductor 4 having a thermal conductivity of 10 W / m · K or more is not particularly limited, and examples thereof include aluminum, copper, alumina, beryllia, silicon carbide, silicon nitride, aluminum nitride, and a graphite sheet. Especially, since it is excellent in heat dissipation, copper and aluminum are preferable.

  The insulating sheet according to the present invention is suitably used for bonding a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer of a semiconductor device on which a semiconductor element is mounted on a substrate. The insulating sheet according to the present invention adheres a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer of an electronic component device in which electronic component elements other than semiconductor elements are mounted on a substrate. Are also preferably used.

  In the case where the semiconductor element is a power device element for a large current, a higher insulation property or a higher heat resistance is required. Therefore, in such an application, the insulating sheet of the present invention is more preferably used.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. In addition, this invention is not limited to a following example.

  The following materials were prepared.

[Polymer (A)]
(1) Bisphenol A-type phenoxy resin (trade name: E1256, Mw = 51,000, Tg = 98 ° C., manufactured by Japan Epoxy Resin Co., Ltd.)
(2) High heat resistance phenoxy resin (manufactured by Toto Kasei Co., Ltd., trade name: FX-293, Mw = 43,700, Tg = 163 ° C.)
(3) Epoxy group-containing styrene resin (manufactured by NOF Corporation, trade name: Marproof G-1010S, Mw = 100,000, Tg = 93 ° C.)

[Polymers other than polymer (A)]
(1) Epoxy group-containing acrylic resin (manufactured by NOF Corporation, trade name: Marproof G-0130S, Mw = 9,000, Tg = 69 ° C.)

[Epoxy monomer (B1)]
(1) Bisphenol A type liquid epoxy resin (made by Japan Epoxy Resin, trade name: Epicoat 828US, Mw = 370)
(2) Bisphenol F type liquid epoxy resin (made by Japan Epoxy Resin, trade name: Epicoat 806L, Mw = 370)
(3) Trifunctional glycidyldiamine type liquid epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., trade name: Epicoat 630, Mw = 300)
(4) Fluorene skeleton epoxy resin (manufactured by Osaka Gas Chemical Co., Ltd., trade name: ONCOAT EX1011, Mw = 486)
(5) Naphthalene skeleton liquid epoxy resin (Dainippon Ink Chemical Co., Ltd., trade name: EPICLON HP-4032D, Mw = 304)

[Oxetane monomer (B2)]
(1) Benzene skeleton oxetane resin (manufactured by Ube Industries, trade name: etanacol OXTP, Mw = 362.4)

[Monomers other than epoxy monomer (B1) and oxetane monomer (B2)]
(1) Hexahydrophthalic acid skeleton liquid epoxy resin (manufactured by Nippon Kayaku Co., Ltd., trade name: AK-601, Mw = 284)
(2) Bisphenol A type solid epoxy resin (product name: 1003, Mw = 1300, manufactured by Japan Epoxy Resin Co., Ltd.)

[Curing agent (C)]
(1) Alicyclic skeleton acid anhydride (manufactured by Shin Nippon Chemical Co., Ltd., trade name: MH-700)
(2) Aromatic skeleton acid anhydride (manufactured by Sartomer Japan, trade name: SMA resin EF60)
(3) Polyalicyclic skeleton acid anhydride (manufactured by Shin Nippon Rika Co., Ltd., trade name: HNA-100)
(4) Terpene skeleton acid anhydride (trade name: Epicure YH-306, manufactured by Japan Epoxy Resin Co., Ltd.)
(5) Biphenyl skeleton phenolic resin (Madewa Kasei Co., Ltd., trade name: MEH-7851-S)
(6) Allyl skeleton phenol resin (product name: YLH-903, manufactured by Japan Epoxy Resin Co., Ltd.)
(7) Triazine skeleton phenolic resin (Dainippon Ink Chemical Co., Ltd., trade name: Phenolite KA-7052-L2)
(8) Melamine skeleton phenol resin (manufactured by Gunei Chemical Industry Co., Ltd., trade name: PS-6492)
(9) Isocyanur-modified solid dispersion type imidazole (imidazole curing accelerator, manufactured by Shikoku Kasei Co., Ltd., trade name: 2MZA-PW)

[Filler (D)]
(1) Spherical alumina (Denka Co., Ltd., trade name: DAM-10, average particle size 10 μm, thermal conductivity 36 W / m · K)
(2) Boron nitride (manufactured by Showa Denko KK, trade name: UHP-1, average particle size 8 μm, thermal conductivity 60 W / m · K)
(3) Aluminum nitride (manufactured by Toyo Aluminum Co., Ltd., trade name: TOYALNITE-FLX, average particle size 14 μm, thermal conductivity 200 W / m · K)

[Fillers other than filler (D)]
Fumed silica (trade name: MT-10, manufactured by Tokuyama Corporation, thermal conductivity 1.3 W / m · K)

[Additive]
(1) Epoxysilane coupling agent (Shin-Etsu Chemical Co., Ltd., trade name: KBE403)

[solvent]
(1) Methyl ethyl ketone

Example 1
Using a homodisper type stirrer, each raw material was blended and kneaded in the proportions shown in Table 1 below (the blending unit is by weight) to prepare an insulating material.

  The insulating material was applied to a release PET sheet having a thickness of 50 μm to a thickness of 100 μm and dried in an oven at 90 ° C. for 30 minutes to produce an insulating sheet on the PET sheet.

(Examples 2 to 20 and Comparative Examples 1 to 4)
An insulating material was prepared in the same manner as in Example 1 except that the types and blending amounts of the raw materials used were as shown in Tables 1 and 2 below, and an insulating sheet was produced on the PET sheet.

(Evaluation of Examples and Comparative Examples)
The following items were evaluated for each insulating sheet obtained as described above.

(1. Handling property)
A test sample was prepared by cutting a laminated sheet having a PET sheet and an insulating sheet formed on the PET sheet into a 460 mm × 610 mm square. In this test sample, the handling property when the uncured insulating sheet was peeled from the PET sheet at room temperature (23 ° C.) was evaluated according to the following criteria.

A: The insulation sheet is not deformed and can be easily peeled off. Very easy to handle without tackiness ○: Insulation sheet is not deformed and can be easily peeled off, but it is slightly tacky and requires care in handling △: Insulation sheet can be peeled off, but sheet elongation or breakage occurs ×: The insulating sheet cannot be peeled off

(2. Independence)
In the evaluation of the handling property, the squares of the uncured insulating sheet after being peeled off from the PET sheet are fixed, and the insulating sheet is suspended in the air so that the squares are positioned in the horizontal direction. I left it alone. The deformation of the insulating sheet after being allowed to stand was observed, and the self-supporting property was evaluated according to the following criteria.

A: The insulating sheet is hardly bent downward, and the insulating sheet has a deflection distance (degree of deformation) within 1 cm. ○: The insulating sheet is slightly bent downward, and the insulating sheet is vertical. Deflection distance (deformation degree) within 3 cm within Δ: Insulation sheet is bent downward, insulation sheet vertical deflection distance (deformation degree) is within 5 cm ×: Insulation sheet is bent downward The deflection distance (degree of deformation) in the vertical direction of the insulating sheet exceeds 5 cm, or the insulating sheet breaks.

(3. Glass transition temperature)
Using a differential scanning calorimeter “DSC220C” manufactured by Seiko Instruments Inc., the glass transition temperature of the uncured insulating sheet was measured at a heating rate of 3 ° C./min.

(4. Flexural modulus)
Using a universal testing machine RTC-1310A (manufactured by Orientec Co., Ltd.), in accordance with JIS K 7111, a test piece having a length of 8 cm, a width of 1 cm and a thickness of 4 mm was obtained under the conditions of a distance between supporting points of 6 cm and a speed of 1.5 mm / min. By measuring, the bending elastic modulus at 25 ° C. of the uncured insulating sheet was measured.

  The insulating sheet was cured at 120 ° C. for 1 hour and then at 200 ° C. for 1 hour to obtain a cured product of the insulating sheet. Using a universal testing machine (Orientec Co., Ltd.) in the same manner as the uncured insulating sheet, a test piece having a length of 8 cm, a width of 1 cm, and a thickness of 4 mm was obtained at a distance between fulcrums of 6 cm and a speed of 1. By measuring under the condition of 5 mm / min, the flexural modulus at 25 ° C. of the cured product of the obtained insulating sheet was measured.

(5. Elastic modulus)
Using a rotary dynamic viscoelasticity measuring device VAR-100 (manufactured by Rheologicala Instruments), a disk-shaped uncured insulating sheet sample with a diameter of 2 cm is used, and oscillation is performed by a parallel plate with a diameter of 2 cm. The tan δ at 25 ° C. of the uncured insulating sheet was measured under the conditions of the strain control mode, the starting stress of 10 Pa, the frequency of 1 Hz, and the strain of 1%. In addition, the maximum value of tan δ of the insulating sheet when the insulating sheet in the uncured state is heated from 25 ° C. to 250 ° C. is obtained by adding the uncured insulating sheet sample to the measurement conditions and increasing the rate of temperature increase. It was measured by raising the temperature from 25 ° C. to 250 ° C. at 30 ° C./min.

(6. Thermal conductivity)
The thermal conductivity of the insulating sheet was measured using a thermal conductivity meter “rapid thermal conductivity meter QTM-500” manufactured by Kyoto Electronics Industry Co., Ltd.

(7. Heat dissipation)
An insulating sheet is sandwiched between an aluminum plate having a thickness of 1 mm and an electrolytic copper foil having a thickness of 35 μm, and the insulating sheet is press-cured at 120 ° C. for 1 hour and further at 200 ° C. for 1 hour while maintaining a pressure of 4 MPa with a vacuum press machine. A copper-clad laminate of the base substrate was formed. The copper foil surface of the obtained copper-clad laminate was pressed against a smooth surface heating element having the same size controlled at 100 ° C. with a pressure of 20 kgf / cm ² , and the temperature of the aluminum plate surface was measured with a thermocouple. The heat dissipation was judged according to the following criteria from the difference in temperature.

◎: Temperature difference between the heating element and the aluminum plate surface is within 3 ℃ ○: Temperature difference between the heating element and the aluminum plate surface exceeds 3 ℃, within 6 ℃ △: Temperature difference between the heating element and the aluminum plate surface is 6 ℃ Exceeding and within 10 ° C ×: Temperature difference between heating element and aluminum plate exceeds 10 ° C

(8. Peeling strength)
An insulating sheet is sandwiched between an aluminum plate having a thickness of 1 mm and an electrolytic copper foil having a thickness of 35 μm, and the insulating sheet is press-cured at 120 ° C. for 1 hour and further at 200 ° C. for 1 hour while maintaining a pressure of 4 MPa with a vacuum press machine. A copper-clad laminate of the base substrate was formed. The copper foil of the obtained metal base substrate is etched to form a strip of copper foil having a width of 10 mm, and the peeling strength when the copper foil is peeled from the substrate at a pulling speed of 50 mm / min at an angle of 90 ° C. Was measured.

(9. Dielectric breakdown voltage)
An insulating sheet cut into 100 mm × 100 mm square was cured in a 120 ° C. oven for 1 hour and further in a 200 ° C. oven for 1 hour to prepare a test sample. Using a withstand voltage tester (MODEL7473, manufactured by EXTECH Electronics), the voltage was increased at a rate of 1 kV / sec, and the dielectric breakdown voltage of the test sample was measured.

(10. Solder heat resistance)
The copper-clad laminate produced by the above (8) evaluation of the peel strength was cut out to a size of 50 mm × 60 mm. This was floated in a solder bath at 288 ° C. with the copper foil side facing down, and the time until the copper foil swelled or peeled off was measured and judged according to the following criteria.

◯: No swelling or peeling even after 3 minutes △: Swelling and peeling occurs after 3 minutes and before 3 minutes passed ×: Swelling and peeling occurs before 1 minute passes. Shown in Tables 1 and 2.

FIG. 1 is a partially cutaway front sectional view schematically showing a laminated structure according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated structure 2 ... Conductive layer 2a ... Surface 3 ... Insulating layer 4 ... High thermal conductor

Claims (10)

An insulating sheet used to adhere a high thermal conductor having a thermal conductivity of 10 W / m · K or more to a conductive layer,
A polymer (A) having a weight average molecular weight of 30,000 or more;
An epoxy monomer (B1) having an aromatic skeleton and having a weight average molecular weight of 600 or less and / or an oxetane monomer (B2) having an aromatic skeleton and having a weight average molecular weight of 600 or less;
A curing agent (C) which is a phenol resin, or an acid anhydride having an aromatic skeleton or an alicyclic skeleton, a water additive thereof or a modified product thereof;
Containing a filler (D) having a thermal conductivity of 30 W / m · K or more,
In a total of 100% by weight of the resin component in the insulating sheet containing the polymer (A), the epoxy monomer (B1) and / or the oxetane monomer (B2), and the curing agent (C), the polymer ( A) is a proportion of 20 to 60% by weight, the epoxy monomer (B1) and / or the oxetane monomer (B2) is a proportion of 10 to 60% by weight, and the polymer (A), the epoxy monomer (B1) and And / or the total amount with the oxetane monomer (B2) is less than 100% by weight, respectively,
The glass transition temperature of the uncured insulating sheet is 25 ° C. or lower,
The bending elastic modulus at 25 ° C. of the uncured insulating sheet is in the range of 10 to 1000 MPa, and when the insulating sheet is cured, the bending elastic modulus at 25 ° C. of the cured insulating sheet is 1000 to 1000. In the range of 50000 MPa,
The tan δ of the uncured insulating sheet at 25 ° C. measured using a rotary dynamic viscoelasticity measuring device is in the range of 0.1 to 1.0, and the insulating sheet in the uncured state is 25 ° C. An insulating sheet, wherein the maximum value of tan δ of the insulating sheet when the temperature is raised from 250 to 250 ° C. is 1.0 to 5.0.   The insulating sheet according to claim 1, wherein the polymer (A) has an aromatic skeleton.   The insulating sheet according to claim 1 or 2, wherein the polymer (A) is a phenoxy resin.   The curing agent (C) is an acid anhydride having a polyalicyclic skeleton, an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive thereof, or The insulating sheet according to any one of claims 1 to 3, which is a modified product thereof. The insulating sheet according to claim 4, wherein the curing agent (C) is an acid anhydride represented by any of the following formulas (1) to (3).

In said formula (3), R1 and R2 show hydrogen, a C1-C5 alkyl group, or a hydroxyl group each independently.   The insulating sheet according to any one of claims 1 to 3, wherein the curing agent (C) is a phenol resin having a melamine skeleton or a triazine skeleton, or a phenol resin having an allyl group.   The filler (D) according to any one of claims 1 to 6, wherein the filler (D) is at least one selected from the group consisting of alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, and magnesium oxide. The insulating sheet described.   The insulating sheet according to any one of claims 1 to 6, wherein the filler (D) is spherical alumina and / or spherical aluminum nitride.   The conductive layer is laminated | stacked through the insulating layer on the at least single side | surface of the high heat conductor whose heat conductivity is 10 W / m * K or more, This insulating layer is any one of Claims 1-8. A laminated structure formed by curing an insulating sheet.   The laminated structure according to claim 9, wherein the high thermal conductor is a metal.

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